The TARDIS remains infected (since Cat's Cradle: Witch mark). The Doctor meets Kadiatu Lethbridge-Stewart, who has been collecting information on the Doctor's appearances on Earth, and who later builds her own time machine and leaves Earth. Deciding that too much is known of him on Earth, the Doctor arranges to have all the information on his activities on Earth erased.

My opinion

Ben Aaronovitch, apparently, has a few problems meeting deadlines. Rumour has it that he delivered the first draft of Transit to the publishers only days before the final manuscript had to be sent to the printers, and the final published version is in fact the first draft with only a hurried edit for sense and literals. If this story is true, then Aaronovitch's meticulous world-building in this book is truly amazing. Aaronovitch has built this world incredibly convincingly. It is a world still recovering from a massive war with the Ice Warriors, and the fact that it is such bleak and violent world may be the reason many lovers of the relatively innocent tv show found this such a shock to the system. On the original show they never had as a character a prostitute who chewed kola nuts to "keep her awake and take the semen taste out of her mouth".

This is a book that has polarised opinion about it. It usually comes right near the bottom in many surveys of favourite stories, but is cited by many later Doctor Who authors as a major influence. Personally, I think it's brilliant, and easily one of the best of the early Doctor Who books. It certainly owes a lot to William Gibson and cyberpunk in general, but carries it off so well that I can certainly forgive it that.

Quick outline

The solar system in 2119 is fully colonised by Earth, and linked by a subspace mass transit system. On the thirtieth anniversary of Earth's victory over Mars, the transit authority (the STS) plans to open a tunnel to Acturus, incorporating Earth colonies in other star systems into the transit system. However, when the tunnel is opened something from the other side of the carrier wave smashes through, and tears right through the Central Line killing everyone it its path. At about this time, the Doctor and Benny arrive at King's Cross station, and while the Doctor manages to fall to safety, Benny and the TARDIS are swept away to the end of the line, Lowell Depot on Pluto. Benny survives the journey but is possessed by the force that swept her away. The tunnel to Arcturus is quickly shut down, but the transit system has already been invaded.

The Doctor meets Kadiatu, a university student who, the Doctor soon discovers, has been collecting information on the Doctor and time travel. The Doctor also learns that she is a product of genetic modification research, created to be a perfect soldier but rescued from her creators and raised by an African descendant of the Doctor's old friend Brigadier Alistair Lethbridge-Stewart. The Doctor decides to keep an eye on her, and she also wishes to stay close to him to learn more of time travel, and so they look for Benny together. Meanwhile, other users of the transit system are being affected by the invading force, and being converted into strange cybernetically-enhanced creatures.

Benny, affected by the force possessing her, meets and befriends Zamina, a prostitute living and working at the Stop, the slum neighbourhood around Lowell Depot on Pluto. Benny convinces Zamina to take her to the leader of one of the local gangs, who she convinces she can help take control of the Stop. It is all a ruse, however, to cause a major disruption, and Benny's manipulations result in a major outbreak of gang warfare. The Stop is evacuated, and, after an encounter with the Doctor and Kadiatu in which Benny nearly kills the Doctor, Benny and Zamina are evacuated to Mars.

Losing track of Benny, the Doctor and Kadiatu, along with Kadiatu's new lover Blondie, go to the Doctor's house on Allen Rd, in Kent, where the Doctor considers the situation. Learning about strange things happening in the transit system before the tunnel to Arctutus was opened he deduces that the transit system, having grown so complicated it now resembles a neural network, has evolved its own intelligence. He contacts this new sentience, and learns that the invading force is a sort of computer virus from another dimension. Meanwhile, Benny's distance from the transit system has apparently weakened the invading force's control of her mind, and she is able to get a message to the Doctor telling him where she is.

The Doctor and Kadiatu follow Benny to Mars, where she attempts to reach the STS control centre, but is stopped by Kadiatu, who kills her. It turns out, however, that they were following not Benny, but one of the modified transit users made to look like Benny and sent as a decoy. The Doctor and Kadiatu return to Earth but are too late to prevent Benny achieving her goal. Another of the modified passengers is sent to overload STS's reactors, resulting in a flood of power and the tunnel to Arcturus is opened again.

The Doctor travels through the transit system to the entrance of the Arcturus tunnel, where he arrives in time to see Benny possessed by the full intelligence of the invading force, of which only a portion had arrived last time the tunnel was open. The Doctor is able to use a blast of energy from the TARDIS to send the nameless intelligence (which the Doctor has dubbed "Fred") back down the tunnel to its own dimension, taking Benny with it. The Doctor follows and a battle of will ensues in Fred's home dimension, where perception shapes reality. The Doctor is on the verge of being defeated by Fred when Kadiatu arrives in the form of a black leopard and attacks Fred. While Fred is distracted the Doctor is able, with the additional help of the intelligence of the transit system, to force Fred out of Benny's mind. The Doctor, Benny and Kadiatu are able to escape Fred's dimension and return to Earth victorious just before the tunnel collapses.

Later, having decided that too much is known about him on Earth, the Doctor visits the computer system where most of Earth's historical records are kept, and arranges to have all record of his activities on Earth removed (in the process befriending the newly-evolved artificial intelligence, and giving it tips on how to get along with humans; the intelligence names itself FLORANCE, hires itself some lawyers and declares its independence), and the Doctor and Benny resume their travels. Later still, Kadiatu completes her time travel research, builds her own time machine and leaves Earth.